It is known in the art of subterranean drilling to use a so-called “top drive” to connect a section, also known as a “joint,” of well bore casing above a drilling rig floor to the upper end of a casing string substantially disposed in the well bore. Such casing strings, commonly termed “surface casing,” may be set into the well bore as much as 3,000 feet (914.4 meters), and typically about 1,500 feet (457.2 meters), from the surface.
Examples of methods and apparatus for making casing joint connections to a casing string are disclosed in U.S. Pat. Nos. 6,742,584 and 7,137,454, the disclosure of each of which patents is incorporated herein by this reference.
It is known in the art of subterranean drilling to drill and ream with casing, using a drilling or reaming shoe including a cutting structure thereon to drill a well bore, or to ream an existing well bore to a larger diameter, to remove irregularities in the well bore, or both. It would be highly desirable for the subterranean drilling industry to employ a top drive to apply weight on the casing in combination with casing rotation to drill or ream with casing using a drilling or reaming device at the distal end of the casing string. Additionally, improved casing spears for such applications would be desirable.